Vehicles equipped with an internal combustion engine generally using gasoline or heavy oil as fuel have a serious influence on environmental pollution and air pollution. Therefore, a great of effort has been made to develop electric vehicles or hybrid vehicles in recent years to reduce the air pollution.
Recently, high-output rechargeable batteries using non-aqueous electrolyte with high energy concentration have been developed. The high-output rechargeable battery are connected in series to implement a large-capacity rechargeable battery, in order to be used in apparatuses requiring a large amount of power for operating a motor, such as the electric vehicles.
As described above, one large-capacity rechargeable battery (hereafter, referred to as battery”) is commonly composed of a plurality of rechargeable batteries connected in series. In the battery, particularly a battery for HEVs, several or tens of rechargeable batteries are alternately charged and discharged, such that it is required to manage the batteries such that they maintain appropriate operation by controlling the charging and discharging.
For this configuration, a BMS (Battery Management System) that manages the general states of the battery is provided. The BMS estimates SOC by detecting voltage, current, and temperature etc. of the battery and performing calculation, and controls the SOC to make the fuel efficiency of vehicles best.
FIG. 1 is a diagram showing the configuration of a battery management system according to the related art.
As shown in FIG. 1, the existing management system includes a battery pack formed by laminating battery unit cell in a line, a battery management system is disposed apart from the battery pack, and each unit cell of the battery pack is connected with the battery management system. Therefore, each of n unit cells are connected by two wires, such that information on the n unit cells is sensed and the operation is controlled. In this configuration, the battery cells should be connected to one battery management system such that the battery management systems senses voltage and temperature of the unit cells; therefore, the wire harness become necessarily complicated.
Therefore, the length of the wires connecting the battery management system with the battery pack increases, such that the cost increases and a large volume is required. Further, since the battery management system is disposed apart from the unit cells, spaces for them should be ensured.
Further, the lengths of the wires from the unit cells to the battery management system are different for each wire, such that it is difficult to expect accurate sensing because voltage drops due to wire resistance are different.
Further, it is required to redesign the battery pack case protecting the unit cells, the wires for sensing cell voltage, connectors that connect the wires with the slave battery management modules, and the cell voltage and temperature sensing circuit, in order to change the number of unit cells due to change of voltage of the battery pack.